Global Challenges/Chemistry Solutions

Our Sustainable Future: Small generator, big applications

May 29, 2009

A schematic illustration shows the microfiber
nanowire hybrid nanogenerator, which is the basis
of using fabrics for generating electricity.
Credit: Prof. Z.L. Wang and Dr. X.D.
Wang, Georgia Institute of Technology

Summary

Today’s topic focuses on sustainability,
with a discovery that could help make
today’s landfill-bound batteries obsolete.
Imagine if all you had to do to charge
your iPod or your BlackBerry was to
wave your hand, or stretch your arm,
or take a walk?

Imagine if all you had to do to charge your iPod or your BlackBerry was to wave your hand, or stretch your arm, or take a walk? You could say goodbye to batteries and never have to plug those devices into a power source again.

In research presented at the American Chemical Society’s 237th National Meeting, scientists from Georgia describe technology that converts mechanical energy from body movements or even the flow of blood in the body into electric energy that can be used to power a broad range of electronic devices without using batteries.

“If the battery is large, that means that the integration of the sensor and battery is large, so we have reduced the entire system and called it a nanosystem or a self-powered system. Because the energy requirements are so low, we can use the energy found in the environment. So what is the energy available? When I talk to you, the resulting sonic wave is energy – vibration, noises, all of this is energy around us. If we could harvest this energy we can have particular applications.”

That was Zhong Lin Wang, lead researcher of the report. Wang, a Regents’ Professor, School of Material Science and Engineering at the Georgia Institute of Technology, says this research will have a major impact on defense technology, environmental monitoring, biomedical sciences and even personal electronics. The new “nanogenerator” could have countless applications, among them a way to run electronic devices used by the military when troops are far in the field.

“For example, in vivo biosensors and environmental monitoring sensors are very tiny sensors that we could implant in our own biological system. Implants are very difficult to fish out and change the battery, so we want to use our biological energy, the energy flow of our bloodstream, heart beating, and muscle stretching, to generate electricity and power these small devices. We could monitor our sugar levels, blood pressure and many other disease control measurements. With this and advances in nanotechnology, we can play a very important role for self-powered nanosystems.”

The researchers harvested energy from the environment by converting low-frequency vibrations into electricity. Those vibrations came from simple body movements, the beating of the heart or movement of the wind. They did so with zinc oxide nanowires that conduct the electricity. The zinc oxide nanowires are piezoelectric — they generate an electric current when subjected to mechanical stress. The diameter and length of the wire are 1/5,000th and 1/25th the diameter of a human hair.